Halogenated hydrocarbons, C2 – C2 - Analysis of halogenated hydrocarbons in hydrocarbon/water matrix

Importance of the topic

Volatile halogenated hydrocarbons are widely used in industrial and environmental applications but pose analytical challenges due to their volatility, polarity and potential co-elution with hydrocarbon matrices.
Accurate determination at low ppm levels in complex hydrocarbon/water samples is critical for environmental monitoring, process control and quality assurance.

Objectives and study overview

This application note demonstrates a gas chromatographic method with an electrolytic conductivity detector (ELCD) to quantify C1–C2 halogenated hydrocarbons in a 50% hydrocarbon/50% moisture matrix.
The primary goals included:

• Achieving detection and quantification at 1–4 ppm concentration levels.
• Minimizing co-elution of target analytes with hydrocarbon components.
• Ensuring method accuracy better than ±5%.

Methodology and instrumentation

A wide-bore gas chromatograph was operated under the following conditions:

• Column: Agilent PoraPLOT U (0.53 mm × 25 m, df = 20 µm).
• Column temperature: 150 °C.
• Carrier gas: Helium at 80 kPa (0.8 bar).
• Injector: Split mode at 200 °C.
• Detector: ELCD in chloride mode, reactor temperature 850 °C, hydrogen as reactor gas, n-propanol as electrolyte solvent.
• Sample matrix: 50% hydrocarbon/50% nitrogen with analyte concentrations between 1 and 4 ppm.

Main results and discussion

• The polar porous polymer column effectively separated chlorinated methanes and ethanes from the hydrocarbon matrix, reducing co-elution.
• Measured concentrations closely matched expected values (chloromethane 1 ppm, vinyl chloride 2 ppm, chloroethane 3.5 ppm) with accuracy within 5%.
• Baseline stability and detector sensitivity ensured reliable quantification of target compounds at trace levels.

Benefits and practical applications of the method

• High selectivity for halogenated species in the presence of complex hydrocarbon backgrounds.
• Rapid analysis suitable for environmental monitoring and industrial process QC.
• Robust performance with minimal maintenance due to stable ELCD operation.

Future trends and application possibilities

• Integration with automated sampling for real-time monitoring of fugitive emissions.
• Extension to other halogenated compounds (e.g., brominated or fluorinated analytes) using optimized electrolytes.
• Coupling with mass spectrometry for enhanced identification of unknown halogenated species.

Conclusion

The described GC-ELCD method provides accurate, sensitive and reliable quantification of low-level halogenated hydrocarbons in hydrocarbon/water matrices. Its high selectivity and robust performance make it a valuable tool for environmental and industrial analyses.

Applied instrumentation

• Gas chromatograph with wide-bore inlet assembly.
• Agilent PoraPLOT U column (0.53 × 25 m, 20 µm df).
• ELCD detector in chloride mode (reactor temperature 850 °C, H₂ gas, n-propanol electrolyte).

Reference

• Agilent Technologies, Inc. Application Note A01324: Analysis of Halogenated Hydrocarbons in Hydrocarbon/Water Matrix, 2011.